/printf

Team Project - printf

Primary LanguageC

0x11. C - printf

Description.

The printf function sends formatted output to stdout. A custom _printf() for learning purposes was developed by cohort 9 students, igwe felix chinedu Igwe and Aminu Shaibu. _printf() function format string is a character string, beginning and ending in its initial shift state, if any. These arguments are placed using the percentage '%' operator.

Resources

Secrets of printf by Thomas Samuel.

Authorized functions and macros.

write (man 2 write),

malloc (man 3 malloc),

free (man 3 free),

va_start (man 3 va_start),

va_end (man 3 va_end),

va_copy (man 3 va_copy),

va_arg (man 3 va_arg)

Compilation

The code must be compiled this way:

*$ gcc -Wall -Werror -Wextra -pedantic -std=gnu89 .c

As a consequence, be careful not to push any c file containing a main function in the root directory of your project (you could have a test folder containing all your tests files including main functions)

The main files will include your main header file (main.h): #include main.h

Use & Examples

Prototype: int _printf(const char *format, ...); Use - General: _printf("format string", var1, var2, ...);

Examples:

  • Basic String: _printf("%s Alx", "Hello");`

    • Output: Hello Alx

  • Print integers: _printf("This is an array element: arr[%d]:%c", 32, arr[32]);`

    • Output: This is an array element arr[32]:A

Many other specifiers and flags were added and by combinig those the _printf() function generate a different ouput. The following list are the specifiers and flags allowed.

Use & Examples.

Specifiers.
Specifier Output Examples
c Character y
d or i Signed integer 1024, -1024
s String of characters Hello Alx
b Binary Representation of unsigned integer 01010110
u Unsigned integer 1024
o Unsigned octal 432
x Unsigned hexadecimal integer 3ca
X Unsigned hexadecimal integer (uppercase) 3CA
S String with hex-ascii value replacing special chars \x0A\x0A
p Pointer address 0x403212
r Reversed string of characters dlroW olleH
R ROT13 Translation of string Uryyb
Flags (In development...)
Flag Description
- Left-justify the output within the field width that was given; Right justification is the default (see width sub-specifier).
+ Preceeds the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign.
(space) If no sign is going to be written, a blank space is inserted before the value.
# Used with o, x or X specifiers the value is preceeded with 0, 0x or 0X respectively for values different than zero.
0 Left-pads the number with zeroes (0) instead of spaces when padding is specified (see width sub-specifier).
Width (In development...)
Width Description
(number) Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.
* The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

Precision (In development...)

.Precision Description
.(number) For integer specifiers (d, i, o, u, x, X): precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For s: this is the maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. If the period is specified without an explicit value for precision, 0 is assumed.

Length modifiers (In development...)

Modifier/Specifier d & i u, o, x, X c s p
none int unsigned int int char pointer void pointer
h short int unsigned short int
l long int unsigned long int

Files contained in this repository

Name Information Relevant Files
main.h Header file with the data type struct, standard libraries and custom prototypes. *.c compilation
_printf.c Main printf function file. Calls other functions. printf_(name of var).c file
printf_37.c Contains percentage print function. None
printf_int.c Contains decimal and integer functions. None
printf_char.c Custom function for char data type. None
printf_sting.c Function that calls string type variable. None
printf_bin.c Function that gets the binary None
printf_oct.c Functions that returns octal number. None
printf_hex.c Calls hexadecimal numbers (lowercase). None
printf_HEX.c Calls hexadecimal numbers (Uppercase). None
printf_unsigned.c Returns an unisgined data type. None
printf_hex_aux.c Auxiliar function for hexadecimal specific functions (lowercase). printf_exclusive_string.c
printf_HEX_aux.c Auxiliar function hexadecimal specific functions (Uppercase). printf_p.c
printf_exclusive_string.c Returns a string and non readable characters are printed in hexadecimal numbers (Lowercase). printf_hex_aux.c
printf_srev.c Returns a string in reverse. None
printf_rot13.c Returns a string in Rot13. None
printf_str.c Auxiliar functions such as strlen and strcpy. None
_putchar.c Custom putchar function. None

Tasks required for this project

  1. I am not going anywhere. You can print that wherever you want to. I'm here and I am a Spur for life1. I am not going anywhere. You can print that wherever you want to. I'm here and I am a Spur for life.

Write a function that produces output according to a format. Handle the following conversion specifiers:

  • c
  • s
  • %
  1. Education is when you read the fine print. Experience is what you get if you dont

Handle the following conversion specifiers:

  • d
  • i
  1. Just because its in print doesn't mean its the gospel

Create a man page for the function

  1. With a face like mine, I do better in print

Handle the following conversion specifiers:

  • b
  1. What one has not experienced, one will never understand in print

Handle the following conversion specifiers:

  • u
  • x
  • o
  • x
  • X
  1. Nothing in fine print is ever good news

Use a local buffer of 1024 chars in order to call write as little as possible.

  1. Handle the following custom conversion specifier
  • S : prints the string.
  • Non printable characters (0 < ASCII value < 32 or >= 127) are printed this way: \x, followed by the ASCII code value in hexadecimal (upper case - always 2 characters).
  1. How is the world ruled and led to war? Diplomats lie to journalists and believe these lies when they see them in print

Handle the following conversion specifier: p

  1. The big print gives and the small print takes away

Handle the following flag characters for non-custom conversion specifiers:

  • ´+´
  • space
  • ´#´
  1. Sarcasm is lost in print

Handle the following length modifiers for non-custom conversion specifiers:

  • l
  • h Conversion specifiers to handle: d, i, u, o, x, X
  1. Print some money and give it to us for the rain forests

Handle the field width for non-custom conversion specifiers.

  1. The negative is the equivalent of the composer's score, and the print the performance

Handle the precision for non-custom conversion specifiers.

  1. It's depressing when you're still around and your albums are out of print

Handle the 0 flag character for non-custom conversion specifiers.

  1. Every time that I wanted to give up, if I saw an interesting textile, print what ever, suddenly I would see a collection

Handle the - flag character for non-custom conversion specifiers.

  1. Print is the sharpest and the strongest weapon of our party

Handle the following custom conversion specifier:

  • r : prints the reversed string
  1. The flood of print has turned reading into a process of gulping rather than savoring.

Handle the following custom conversion specifier:

  • R: prints the rot13'ed string
  1. *

All the above options work well together.

Authors ©

  • Aminu Shaibu.
  • Igwe felix chinedu Igwe.